An electromagnetic wave is referred to as ultraviolet light, infrared light, a microwave, a terahertz wave or the like depending on a wavelength thereof. The technology for measuring various characteristics of a substance by using an electromagnetic wave is generally referred so as spectroscopic measurement or spectroscopy and a measuring device thereof is referred to as a spectroscopy device. Herein, a phenomenon which can be observed is greatly varied depending on a wavelength range of an electromagnetic wave to be used. For example, referring to a phenomenon of a molecule, it is possible to observe an electronic state for ultraviolet light, a vibration state for infrared light and a rotation state for a microwave, respectively.
Moreover, spectroscopy method is classified into absorption spectroscopy method or emission spectroscopy method depending on a physical quantity to be measured by an electromagnetic wave. The absorption spectroscopy method causes an electromagnetic wave to be incident on a sample and measures a physical property or chemical property of a sample based on a change in the electromagnetic wave which is caused by an interaction of the electromagnetic wave and the sample during passage through the sample or reflection thereof. The emission spectroscopy method emits an electromagnetic wave from the sample by any method and measures a strength of the electromagnetic wave.
In order to measure how to vary a physical quantity to be measured with passage of time, time domain spectroscopy is performed. The time domain spectroscopy method serves to measure a transient spectrum by using the ultrashort pulse laser, thereby enabling observation of a state in which even a very quick reaction on a Femtosecond level progresses. Terahertz time domain spectroscopy method serves to perform Fourier transformation over a time waveform of an electromagnetic wave to be obtained by directly measuring a waveform of a terahertz wave, thereby acquiring information about an amplitude and a phase of the terahertz wave.
A substance to be measured which is a spectroscopic measuring target includes gaseous, solid-state and liquid-state configurations and the like. Depending on the respective configurations, there is devised a method of installing a substance to be measured in such a manner that an electromagnetic wave is transmitted properly. In order to perform measurement with high precision over a liquid-state sample, for instance, a sample to be arranged as a measured target in a spectroscopy device is required to be formed so thinly that an electromagnetic wave is transmitted, and furthermore, is to be installed in such a manner that impurities other than a substance to be measured is not mixed therein. In the case in which a liquid sample is subjected to spectroscopic measurement with a terahertz wave, particularly, it is necessary to perform the measurement by making a liquid into a plate-shaped uniform thin film and transmitting a terahertz wave through the plate-shaped part in order to prevent a reduction in an SN ratio of a measuring signal to be detected because of a great absorption effect for the terahertz wave through a water molecule.
In the measurement for a liquid sample, generally, the sample is inserted into a vessel (generally referred to as a solution cell) formed by a material for transmitting an electromagnetic wave, for example, glass and the electromagnetic wave is incident from an outside of the solution cell to measure the electromagnetic wave transmitted through the solution cell. When the liquid sample is inserted into the solution cell and is thus measured, however, spectroscopic information of a cell material is superimposed as a noise on a measuring signal with respect to spectroscopic information of the liquid sample so that the measurement for true spectroscopic information is disturbed.
In consideration of such a problem, conventionally, there is proposed a liquid thinning device which is intended for enabling measurement of spectroscopic information with small noises without using a solution cell (for example, see Patent Document 1). The liquid thinning device described in the Patent Document 1 serves to directly make a liquid sample thin-film shaped by using the nozzle and make a surface wave through a sound wave or an ultrasonic wave on a surface of a liquid film to be generated by a nozzle, thereby reducing a flatness of a liquid film surface and removing an interference of an electromagnetic wave which is a defect of the nozzle.
Patent Document 1: Japanese Laid-Open Patent Publication No. 2011-127950